Petrol 3.5hp Lawnmower

[davidiangould]

Hi folks i recently got a petrol lawn mower it was 2 years old . great running . done a few cuts with it - then it started to cut out - not tick over properly. So i done the usual - clean filter was and dry it 9 foam filter. clean spark plug and leave it apart to make sure it dryed out if it was flooded. it then ran for a while. then stalled and wont start again. I bought brand new spark plug and put it in . i did make an adjustment to a screw with a spring on it attached to the auto choke i think but i maybe should not have done this and this maybe whats causing it not to start - ill add a pic of the screw with spring on it but any advice would be most welcome thanks guys

 

[Burnerman]

A bit more info if you will David, the make of the engine and a picture of the engine and carburettor would be good!
Guess work - its a Briggs motor with the tank below the carburettor, and you've adjusted the mixture screw
John

 

[davidiangould]

it is a Tertiary 3.5 BHP one and ill get on the photos right now

 

[davidiangould]

Untitled

• davidiangould
• 3 Nov 2013
• 1

Untitled

• davidiangould
• 3 Nov 2013
• 1

Untitled

• davidiangould
• 3 Nov 2013
• 1

 

[davidiangould]

the screw is in the third picture with the spring around it -

 

[Burnerman]

These machines are Chinese copies of Briggs and Stratton motors - nothing wrong with that but the parts are not interchangable and in this case, very difficult to get, so we have to make do with what there is.
The screw you mention is likely to be a fast running screw - either way its got nothing to do with the problems you have.
You need to strip the carburettor down for a clean.....in the absence of compressed air you can probably get away with an aerosol can of carburettor cleaner - basically a toluene based solvent.
The carb has to be taken from the engine, the float bowl removed and then turned upside down. This allows the float to be removed, together with the needle jet that allows fuel into the carb.
In the centre of the carb above the float you'll see a brass screw with a slot...this is taken out and thoroughly cleaned with the carb cleaner......likewise any passages or drillings that you can see.
I don't know how far you want to go with this, but if you get stuck in, please be aware that even gaskets are difficult to get - so the idea is, not to trash them.
John

 

[davidiangould]

thanks ill give this a go tomorrow and see if it has helped any

 

[Burnerman]

Best of luck with it....as far as I know, there aren't any springs in the carb to fly away, but if you can identify the needle jet, its usually hooked onto the float.
John

 

[davidiangould]

Best of luck with it....as far as I know, there aren't any springs in the carb to fly away, but if you can identify the needle jet, its usually hooked onto the float.
John

so strip it down . spray with carb cleaner then let dry and replace?? should i spray the whole carb and also the float bit too??

 

[Burnerman]

Basically, once the carb is off the machine, clean the outside with the cleaner so no grot can get inside.
Then, its spanner time to remove the float bowl and flush out any debris that could be visible.....likewise for any pieces that you remove from the carb.
Just one point.....don't use kitchen paper or any cloth to wipe the thing out - the fibres will get in there and cause problems.
Good luck with it!
John

 

[davidiangould]

hi there

managed to strip the mower carb this morning - what do you know? a whole lot of brownish gunge in the bottom of the bowl - no wonder its not started - just need to go pick up the carb cleaner from eaurocarparts will give it a good clean out and fingers crossed its a go .

 

[Burnerman]

Well well.....brownish gunge is rust, which usually means water in the fuel - it takes surprisingly little to cause that!
Its still worth cleaning out the needle jet (above the float - the float comes adrift courtesy of a pin that pulls out) and the brass jets up the carb centre.
Be lucky!
John

 

[davidiangould]

Well well.....brownish gunge is rust, which usually means water in the fuel - it takes surprisingly little to cause that!
Its still worth cleaning out the needle jet (above the float - the float comes adrift courtesy of a pin that pulls out) and the brass jets up the carb centre.
Be lucky!
John

i have totally blasted the carb including the jet as this is where most of the gunk was just in the pipe leading up to it - there was a fair bit in the bowl as well so i have that steping in someon the fluid - want to make sure i get all of it or as much as i can before putting it back on

 

[davidiangould]

right engine running no prob now - the only thing is that the old gasket seems to be too big for the groove between the bowl and the carb - i tried to get it to fit in but it keeps on leaking out a hughe amount of fuel - should i replace that? if so where would be a good pace to get one? just in case i am not putting the gasket in correct twhich way is it supoosed to go - there is a smooth side and there is a slightly grooved side

 

[davidiangould]

found out wat it is carb float pin missing where can i get replacement???